Claude Code Documentation

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Quick Reference ​

Fast lookup guides for common Claude AI operations, commands, and troubleshooting.

┌─────────────────────────────────────────────────────────────────────┐
│                        QUICK REFERENCE HUB                           │
├─────────────────────────────────────────────────────────────────────┤
│                                                                      │
│   Commands & APIs         Templates & Patterns      Troubleshooting │
│   ───────────────        ────────────────────      ──────────────  │
│   • API Endpoints         • Prompt Templates        • Error Codes   │
│   • CLI Commands          • Code Patterns           • Common Issues │
│   • Model Parameters      • System Prompts          • Solutions     │
│                                                                      │
└─────────────────────────────────────────────────────────────────────┘

📋 Reference Guides ​

Most Used Commands ​

Claude API ​

python
# Quick initialization
from anthropic import Anthropic
client = Anthropic()

# Basic message
response = client.messages.create(
    model="claude-3-5-sonnet-20241022",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Your prompt"}]
)

Claude Code CLI ​

bash
# Basic commands
claude-code "What's in this directory?"
claude-code review main.py
claude-code test api/
claude-code "Fix the error in line 42"

# With options
claude-code --model haiku "Quick task"
claude-code --max-tokens 2000 "Long response needed"
claude-code --temperature 0.2 "Precise code generation"

Common Patterns ​

Error Handling ​

python
try:
    response = client.messages.create(...)
except RateLimitError:
    # Wait and retry
except AuthenticationError:
    # Check API key
except Exception as e:
    # Log and handle

Streaming Responses ​

python
with client.messages.stream(...) as stream:
    for text in stream.text_stream:
        print(text, end="")

Model Quick Reference ​

ModelSpeedIntelligenceCostUse Case
Haiku 4.5⚡⚡⚡★★★$Quick responses, simple tasks
Sonnet 4.5⚡⚡★★★★$$Balanced, general purpose
Opus 4.5⚡★★★★★$$$Complex reasoning, coding

Environment Variables ​

bash
# Essential
ANTHROPIC_API_KEY=sk-ant-api03-...

# Optional
ANTHROPIC_MODEL=claude-3-5-sonnet-20241022
ANTHROPIC_MAX_TOKENS=4096
ANTHROPIC_TEMPERATURE=0.7
ANTHROPIC_BASE_URL=https://api.anthropic.com

Keyboard Shortcuts ​

Claude Code ​

ActionShortcutDescription
CancelCtrl+CStop current operation
ClearCtrl+LClear terminal
History↑/↓Navigate command history
CompleteTabAutocomplete files/commands

Quick Debugging ​

Check Installation ​

bash
claude-code --version
claude-code diagnose
claude-code config list

Test Connection ​

python
# test_quick.py
from anthropic import Anthropic
client = Anthropic()
print(client.messages.create(
    model="claude-3-5-haiku-20241022",
    max_tokens=10,
    messages=[{"role": "user", "content": "Hi"}]
).content[0].text)

Rate Limits ​

ModelRequests/minTokens/minTokens/day
Haiku50100,0005,000,000
Sonnet4080,0004,000,000
Opus2040,0002,000,000

Common Error Codes ​

CodeMeaningQuick Fix
401Invalid API keyCheck ANTHROPIC_API_KEY
429Rate limitImplement backoff
500Server errorRetry with exponential backoff
503Service unavailableCheck status.anthropic.com

Useful Snippets ​

Retry Logic ​

python
import time
def retry(func, retries=3):
    for i in range(retries):
        try:
            return func()
        except Exception as e:
            if i == retries - 1: raise
            time.sleep(2 ** i)

Token Counter ​

python
def estimate_tokens(text):
    # Rough estimation
    return len(text) // 4

Response Parser ​

python
def parse_code_blocks(response):
    import re
    pattern = r'```(?:\w+)?\n(.*?)\n```'
    return re.findall(pattern, response, re.DOTALL)

Quick Templates ​

System Prompt ​

python
system = "You are a helpful AI assistant skilled in Python and web development."

Code Review ​

python
prompt = f"Review this code for bugs and improvements:\n```python\n{code}\n```"

Test Generation ​

python
prompt = f"Write comprehensive unit tests for:\n```python\n{code}\n```"

Emergency Contacts ​

Need more details? Check specific guides:

Claude Code Documentation Hub

Based on official Anthropic documentation